This invention relates to a printing apparatus in a system having the printing apparatus and an information processing apparatus such as a personal computer, and to control of the resolution and/or gradation (gray level) of the printing apparatus.
A method of controlling the printing resolution or gray level of a printing apparatus in dependence upon the complexity of the print data and the processing capability of the printing apparatus itself is known in the art.
More page printer comprises a video controller and a printer engine. The video controller receives print data described in Printer Language from a host computer or the like and develops the print data into the image data represented with a dot image matrix. To store one page of image data, large amount of memory capacity is required in the printer. As the paper size or the resolution increases, the number of bits necessary for the memory increases. To reduce the memory capacity, a band buffer technique often uses. In the band buffer technique, a page corresponding to a print image is divided into bands in a sheet feed direction. A plurality of band buffers are cyclically used for each output page, and the developing process for one band buffer and the transmitting the image data from another band buffer to the printer engine are performed in parallel. But, in some cases, like the amount of the print data in one page is too large and these data is overflowed from the print data buffer or the developing process takes too much time to prepare the image data sipping to the printer engine and has occurred the overrun error, the image data can't be printed on the sheet correctly. To alleviate these above situation, there is the method which decreases the amount of time for the developing process or the amount of memory for storing the image data by taking the lower resolution or gradation for processing the image data then the prevailing resolution or gradation.
However, it isn't determined whether takes the lower resolution or gradation until the processing time for all of the band buffer are estimated based on the received print data from host computer for one page or the print data buffer is full, herein the print data are converted into the intermediate code depending on the resolution or gradation in parallel with the printer data receiving.
Accordingly, when the need to lower printing resolution or gradation actually arises, it is necessary to invalidate processing executed thus far based upon the prevailing resolution or gradation delete the above type of the intermediate code and generate a page image whose resolution or gradation is lower than the prevailing resolution or gradation using all of the received data again to produce the image. This is disadvantageous in that rapid printout cannot be performed.